The present invention relates in general to vehicle clutches and in particular to a system for monitoring the rotational speeds of both a clutch brake and a flywheel within a friction clutch assembly and for generating a visual or audible indication when a predetermined condition occurs, such as frictional engagement of the clutch brake or slippage within the friction clutch assembly.
Manual transmissions are widely used in various types of vehicles. In such vehicles, a friction clutch assembly is generally utilized to selectively connect the vehicle engine to the vehicle transmission. The friction clutch assembly includes a plurality of driving input members (including a flywheel) which are connected to the engine, and a plurality of driven output members (including an output shaft) which are connected to the transmission. Means are provided for selectively frictionally engaging the driving input members to the driven output members. When so connected, the flywheel is connected to the output shaft for rotation together. Therefore, the engine is connected to the transmission for supplying power thereto. When the friction clutch assembly is disengaged, the transmission is not driven by the engine, and the transmission may be shifted smoothly from one gear ratio to another before re-engaging the friction clutch assembly.
A release mechanism is provided in the friction clutch assembly to accomplish the selective frictional engagement and disengagement thereof. Typically, the release mechanism includes a bearing which is disposed about the output shaft. The release bearing is axially movable along the output shaft between engaged and disengaged positions. In non-synchronized transmissions, it is well known to further provide a clutch brake about the output shaft to stop the output shaft from rotating when the release bearing is moved to the disengaged position. The clutch brake is disposed about the output shaft (to which it is connected for rotation therewith) between the release bearing and a housing for the friction clutch assembly. When the release bearing is moved to the disengaged position, the clutch brake is frictionally engaged between the release bearing and the housing. Such frictional engagement slows the rotation of the output shaft of the friction clutch assembly so that a smooth gear shifting operation may be effected within the transmission.
The clutch brake is intended to be used only for the limited purpose of stopping the rotation of the output shaft prior to a gear shifting operation. Therefore, the clutch brake should be frictionally engaged only for relatively short periods of time. Unfortunately, because of lengthy and unnecessary frictional engagement, known clutch brake structures are prone to premature wear and failure. Such excessive engagement is commonly referred to as "riding" the clutch brake during a gear shifting operation. Such a situation can occur if the clutch brake is frictionally engaged while upshifting or while the vehicle is rolling to a stop when the transmission is in gear. During such situations, the clutch brake is subjected to significant heat and mechanical loading resulting from the lengthy frictional engagement. Although some experienced vehicle operators can determine by feel when the clutch brake is applied and, therefore, are able to avoid such undesirable excessive frictional engagement, many other vehicle operators are not so skilled. Accordingly, it would be desirable to provide a monitoring system which alerts the vehicle operator when the clutch brake is frictionally engaged in order to prevent premature failure thereof resulting from excessive engagement. It would also be desirable to provide such a monitoring system which alerts the vehicle operator when an undesirable amount of slippage occurs within the friction clutch assembly when it is engaged, indicating that maintenance for the friction clutch assembly is needed.